4.2 Infant mortality rate

Modified on 2012/03/05 16:06 by MDG Wiki Handbook — Categorized as: Goal 4



Goal 4. Reduce child mortality
Target 4.A. Reduce by two-thirds, between 1990 and 2015, the under-five mortality rate


The infant mortality rate (IMR) is the probability that a child born in a specified year will die before reaching the age of one, if subject to current age-specific mortality rates.

This indicator is expressed in terms of deaths per 1,000 live births.

A live birth is the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of the pregnancy, which, after such a separation, breathes or shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached. Each product of such a birth is considered a live birth.

Method of computation
The indicator is calculated by dividing the number of deaths of infants under one year of age in a calendar year by the number of live births in the same year and multiplied by 1,000.

The formula for computing this indicator is as follows:


where IMR(n) is the infant mortality rate for the calendar year n; D (0, n) is the number of infants aged 0 during year n and who died during year n; and B (n) is the number of live births occurring during year n.

Two types of methods exist for calculating the IMR: the direct method and the indirect method. For details on the direct and indirect methods of estimation, see “DEFINITION AND METHOD OF COMPUTATION” for Indicator 4.1.


Although the MDG target relates specifically to under-five mortality, the infant mortality rate is also useful to monitor progress since it represents an important component of under-five mortality. Infant mortality rates are also important because they reflect the social, economic and environmental conditions in which children (and others in society) live, including the quality and accessibility of health care (both in general and at child birth). In addition, data on disease incidence and prevalence (morbidity data) are frequently unavailable, so mortality rates are often used to identify vulnerable populations.


See “SOURCES AND DATA COLLECTION” for Indicator 4.1.


Infant mortality generally shows large disparities across geographical areas and between urban and rural areas. The infant mortality rate may also vary across socioeconomic groups, and is often used to identify social distress in populations. Infants in some ethnic groups might be exposed to higher risks of malnutrition, poorer health and higher mortality; and gender differences may be more pronounced in some social and ethnic groups.

Infant mortality can also be disaggregated into the neonatal and postneonatal periods. Neonatal mortality reflects safe delivery and availability of infant resuscitation, while postneonatal mortality is more influenced by nutrition and infectious diseases.


The infant mortality rate is considered to be a more robust estimate than the under-five mortality rate if data are drawn from vital statistics registrations. On the contrary, when using survey data, infant mortality might be underestimated and under-five mortality rates are considered to be more robust than infant mortality rates. Survey data are subject to survivor selection bias and age truncation. Mothers may misreport their children’s birth dates, current ages or ages at death—perhaps more so if the child has died. The heaping of deaths at age 12 months is especially common. Age heaping may transfer deaths across the one-year boundary and lead to underestimates of infant mortality rates. Also, indirect estimates of the IMR are more depending than U5MR on the choice of model life table.

For more detailed comments on data limitations, see “COMMENTS AND LIMITATIONS” for Indicator 4.1.


Girls have a survival advantage over boys during the first year of life, largely based on biological differences. This is especially so during the first month of life when perinatal conditions are most likely to cause or contribute to death. In later infancy, discrimination against girls in food or medical care may begin to increase their mortality rates relative to boys. A careful examination of gender differences in infant mortality would require disaggregating the infant mortality rate by sex into neonatal (up to 1 month) and postneonatal (1-11 months) components. Although it is possible to do this with DHS data, it should be kept in mind that sampling error can lead to wide confidence intervals for the disaggregations and difficulty in interpreting trends. Such information may also be available from vital registration data.


Infant mortality rates are published annually by the United Nations Children’s Fund (UNICEF) in The State of the World’s Children and by the World Bank in World Development Indicators. They are also included in the World Health Organization’s (WHO) World Health Statistics. These data series may differ, however, because of differences in the methodologies used to estimate data and differences in reporting periods.

For detailed explanations on how global and regional estimates are derived, see “DATA FOR GLOBAL AND REGIONAL MONITORING” for Indicator 4.1.




See “REFERENCES” for Indicator 4.1.